Direct Demonstration of Unified Brønsted−Evans−Polanyi Relationships for Proton-Coupled Electron Transfer Reactions on Transition Metal Surfaces

2020 ◽  
Vol 167 (16) ◽  
pp. 166516
Author(s):  
Hee-Joon Chun ◽  
Zhenhua Zeng ◽  
Jeffrey Greeley
2005 ◽  
Vol 44 (21) ◽  
pp. 7624-7633 ◽  
Author(s):  
David Sarauli ◽  
Roland Meier ◽  
Gao-Feng Liu ◽  
Ivana Ivanović-Burmazović ◽  
Rudi van Eldik

Science ◽  
2019 ◽  
Vol 364 (6439) ◽  
pp. 471-475 ◽  
Author(s):  
Giovanny A. Parada ◽  
Zachary K. Goldsmith ◽  
Scott Kolmar ◽  
Belinda Pettersson Rimgard ◽  
Brandon Q. Mercado ◽  
...  

Electron transfer reactions slow down when they become very thermodynamically favorable, a counterintuitive interplay of kinetics and thermodynamics termed the inverted region in Marcus theory. Here we report inverted region behavior for proton-coupled electron transfer (PCET). Photochemical studies of anthracene-phenol-pyridine triads give rate constants for PCET charge recombination that are slower for the more thermodynamically favorable reactions. Photoexcitation forms an anthracene excited state that undergoes PCET to create a charge-separated state. The rate constants for return charge recombination show an inverted dependence on the driving force upon changing pyridine substituents and the solvent. Calculations using vibronically nonadiabatic PCET theory yield rate constants for simultaneous tunneling of the electron and proton that account for the results.


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